1. Background Art
The proteoglycans of articular cartilage consist of a protein core to which several hundred GAG chains are covalently attached. The major GAG substituents of the proteoglycans of articular cartilage are the chondroitin sulfates (ChS). In adult cartilage Ch-6-S is more abundant than the corresponding 4-sulfated isomer (Ch-4-S) which predominates in articular cartilage of very young animals. Another GAG covalently attached to the core protein of proteoglycans are the keratan sulfates (KS).
These are of smaller molecular weight than the ChS (5000–8000 Da) and are predominately clustered in a domain at the N-terminal end of the proteoglycan core protein known as the G1–G2 interglobular domain. Within the extracellular matrix of articular cartilage hydrated proteoglycan complexes are entrapped in the form of macromolecular aggregates by a three dimensional network of Type II collagen fibres. This unique structural organisation of proteoglycan, water and a fibrous collagen network which is anchored in the subchondral bone plate confers to articular cartilage the biomechanical properties of resilience necessary for normal biomechanical function.
Products of cartilage breakdown in vivo, particularly in arthritis affected joints, have been shown to be antigenic and when released into synovial fluid may provoke synovial inflammation. Once established, synovial inflammation, can alter the metabolism of resident synoviocytes, which are the major cellular source of synovial hyaluronic acid in joints. Inflammatory mediators released from local macrophage and infiltrating leukocytes can also promote increased vascular permeability and the dilution of synovial fluid by plasma fluid, thereby decreasing local hyaluronic fluid concentration. This dilution of hyaluronic acid coupled with a reduction in its molecular size due to abnormal synthesis by synoviocytes results in a substantial decrease in the rheological properties of synovial fluid and consequently its ability to lubricate and protect articular cartilage. Macrophage of the synovium, together with the leukocytes which enter the synovial cavity due to the local inflammation, are also an abundant source of cytokines [eg interleukin-1 (IL1)], procoagulant factors, proteinases and oxygen-derived free radicals including nitric oxide radical. While much of the excess proteolytic activity released into synovial fluid is abrogated by the endogenous inhibitors present, cytokines and free radicals can freely diffuse into cartilage and down-regulate proteoglycans and collagen synthesis by chondrocytes. These proinflammatory mediators can also initiate the production of catabolic proteinases, cytokines and free radicals such as nitric oxide by the cartilage cells which contribute to further articular cartilage matrix destruction via autocrine and paracrine pathways.
Accordingly, in arthritic diseases such as osteoarthritis, multiple tissues of the joint are affected and their excessive breakdown and the concomitant elicitation of an inflammatory reaction can lead not only to the progression of the disease state but also the initiation of symptoms the most common being pain and impairment of joint function.
Glucosamine and chondroitin sulphate (ChS) which are both constituents of cartilage proteoglycans are widely used products for the management of arthritic disease. Commercially available glucosamine is generally isolated from the chitosan present in the exoskeleton of crustacea. By contrast, commercially available chondroitin sulfates are normally manufactured from bovine tissues such as lung and trachea by hydrolysis of the GAG protein core linkage of the cartilage proteoglycan using either chemical or enzymatic procedures. The negatively charged water soluble ChS may be separated and purified from the proteins and peptides also generated by the hydrolysis of cartilage by multiple precipitations with acetone, aliphatic alcohols or the formation of water insoluble complexes with quaternary ammonium salts such as cetyl pyridinium chloride (CPC). However, none of these methods readily remove the contaminating nucleic acids (DNA and RNA) and other intracellular components also released during the chemical or enzymatic disruption of cartilage since these macromolecules are also anionic and would co-precipitate with the anionically charged ChS.
While the consequences of long term human consumption of bovine or other animal nucleic acids in commercial ChS preparations sold as nutraceuticals or food supplements is presently unknown, it should be noted that these intracellular anionic macromolecules are strongly bound to or form complexes with retroviruses and heat/protease resistant prion proteins which have been implicated in the spread of transmissible spongiform encephalopathies variants such as Creutzfeld-Jakob disease, kuru, Gerstmann-Straussler-Scheiner syndrome in humans, scrapie in sheep and goats, and bovine spongioform encaphalopathies in cattle. These intracellular entities could therefore be consumed by the subject in appreciable amounts when they comply with the manufactures recommended dosage of one or more grams of ChS daily for the suppression of the symptoms arising from osteoarthritis and related conditions.
2. General
As used in the specification and claims, the singular form “a,” “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “a fungal pathogen” includes a plurality of fungal pathogens, including mixtures thereof.
As used herein the term “derived” or “derived from” shall be taken to indicate that a specified integer are obtained from a particular source albeit not necessarily directly from that source.
A “composition” is intended to mean a combination of active agent and another compound or composition, inert (for example, an excipient) or another active.
Unless the context requires otherwise or specifically stated to the contrary, integers, steps, or elements of the invention recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements.
The embodiments of the invention described herein with respect to any single embodiment shall be taken to apply mutatis mutandis to any other embodiment of the invention described herein.
Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated step or element or integer or group of steps or elements or integers but not the exclusion of any other step or element or integer or group of elements or integers.
Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations or any two or more of said steps or features.
The present invention is not to be limited in scope by the specific examples described herein. Functionally equivalent products, compositions and methods are clearly within the scope of the invention, as described herein.